Expandable porous mesh bag device and methods of use for reduction, filling, fixation, and supporting of bone

ABSTRACT

The invention provides a method of correcting numerous bone abnormalities including bone tumors and cysts, avascular necrosis of the femoral head, tibial plateau fractures and compression fractures of the spine. The abnormality may be corrected by first accessing and boring into the damaged tissue or bone and reaming out the damaged and/or diseased area using any of the presently accepted procedures or the damaged area may be prepared by expanding a bag within the damaged bone to compact cancellous bone. After removal and/or compaction of the damaged tissue the bone must be stabilized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. patent application Ser. No.09/909,667, filed Jul. 20, 2001 now abandoned, which claims priority toU.S. Provisional Application No. 60/219,853 filed Jul. 21, 2000, theentirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to methods and devices for correcting boneabnormalities and involves the use of a surgical mesh bag which isinserted into a prepared cavity in bone. The bag is inflated using bonereplacement material to expand and fill the cavity.

U.S. Pat. Nos. 5,549,679 and 5,571,189 to Kuslich, describe a device andmethod for stabilizing the spinal segment with an expandable, porousfabric implant for insertion into the interior of a reamed out discwhich is packed with material to facilitate bony fusion. In the presentinvention, a similar bag is used to correct bone abnormalitiesincluding, but not limited to, bone tumors and cysts, tibial plateaufractures, avascular necrosis of the femoral head and compressionfractures of the spine.

U.S. Pat. Nos. 5,108,404 and 4,969,888 to Scholten et al., describe asystem for fixing osteoporotic bone using an inflatable balloon whichcompacts the bone to form a cavity into which bone cement is injectedafter the balloon is withdrawn. The invention requires the use offluoroscopy to monitor the injection and to help guard against cementleakage through fissures in bone. Unfortunately, such leakage is knownto occur in spite of these precautions. Since such leakage may causeserious injury, including paralysis, an improved device and method isneeded.

U.S. Pat. No. 5,972,015 to Scribner et al., describes a system ofdeploying a catheter tube into the interior of a vertebra and expandinga specially configured nonporous balloon therewithin to compactcancellous bone to form a cavity. The Scribner patent approach utilizesa non-porous balloon which is inflated within the bone to causecompression. The cavity thus formed, may then be filled with bonecement. Unfortunately, the bag used by Scribner may be ruptured duringexpansion to compact cancellous bone due to sharp projections foundwithin the cavity to be expanded. Filling the cavity eventually formedcould allow leakage of bone cement out of the bone against vessels ornerves which may cause undesirable complications.

The present invention involves an improvement of all of the previoustechniques and avoids complications that could occur with the system ofU.S. Pat. No. 5,972,015.

All U.S. patents, applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

The art described in this section is not intended to constitute anadmission that any patent, publication or other information referred toherein is “prior art” with respect to this invention, unlessspecifically designated as such. In addition, this section should not beconstrued to mean that a search has been made or that no other pertinentinformation as defined in 37 C.F.R. § 1.56(a) exists.

SUMMARY OF THE INVENTION

The invention provides a method of correcting numerous boneabnormalities including bone tumors and cysts, avascular necrosis of thefemoral head, tibial plateau fractures and compression fractures of thespine. The abnormality may be corrected by first accessing and boringinto the damaged tissue or bone and reaming out the damaged and/ordiseased area using any of the presently accepted procedures, or thedamaged area may be prepared by expanding a bag within the damaged boneto compact cancellous bone. After removal and/or compaction of thedamaged tissue the bone must be stabilized.

In cases in which the bone is to be compacted, the methods and devicesof this invention employ a catheter tube attached to an inflatableporous fabric bag as described in U.S. Pat. Nos. 5,549,679 and 5,571,189to Kuslich, the disclosures of which are incorporated herein byreference. Those bags may be inflated with less fear of puncture andleakage of the inflation medium than thin walled rubber balloons. Theymay also be used over a Scribner balloon to protect the balloon frombreakage and eventually seepage.

The devices of U.S. Pat. Nos. 5,549,679 and 5,571,189 to Kuslich,additionally provide the surgeon with the advantage of safely skippingthe first balloon inflation steps of Scribner and Scholten, by expandingthe bag through introduction of fill material, such as a bone repairmedium thereby correcting the bony defect and deformity and stabilizingit in one step of the procedure.

As indicated above, the damaged bone may be removed by any conventionalreamer. Examples of reamers are described in U.S. Pat. No. 5,015,255;U.S. patent application Ser. No. 09/782,176, to Kuslich et al., entitled“Expandable Reamer” and filed Feb. 13, 2001; and U.S. patent applicationSer. No. 09/827,202 to Peterson et al., entitled “CircumferentialResecting Reamer Tool,” filed Apr. 5, 2001. Other examples of reamersare known and may be used. After the damaged bone or tissue has beenremoved, bone repair medium may then be inserted into the cavity thusformed, via a catheter and expandable fabric bag as described in U.S.Pat. Nos. 5,549,679 and 5,571,189.

Alternatively, either a smaller than desired cavity may be formed intothe bone to be enlarged by compaction or the cavity may be formed onlyby compaction through introduction of fill material into the bag. Ineither case, the bag may be positioned over the inflation balloon whichis then inflated within the bone site to provide the degree ofcompaction required. The bag may then be filled with fill material, suchas bone repair medium while the balloon remains in place within the bag.Alternatively, the balloon may be removed from the bag prior to filingthe bag.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described withspecific reference being made to the drawings in which:

FIG. 1 is a side elevational view of a vertebra that is fractured and inneed of repair;

FIG. 2 is a side view of the vertebra of FIG. 1 being reamed out with areaming tool from the anterior approach;

FIG. 3 is a top view of the vertebra of FIG. 1 showing the reamerforming a pair of cavities within the vertebra from the anteriorapproach;

FIG. 4 is a side elevational view of the vertebra of FIG. 2 showingplacement of an expandable fabric bag of the invention;

FIG. 5 is a top elevational view of the vertebra of FIG. 3 showing asecond of two expandable fabric bags of the invention being positioned;

FIG. 6 is a side view of a vertebra being reamed from a posteriorapproach;

FIG. 7 is a top view of the vertebra of FIG. 6 with a bag in place and asecond cavity being reamed;

FIG. 8 is a side elevational view of the vertebra of FIG. 6 with anexpandable fabric bag of the invention in place;

FIG. 9 is a top view of the vertebra of FIG. 7 with one bag inflated andthe second bag being deployed;

FIG. 10 is a side elevational view showing the vertebra cavity beingexpanded with an expandable fabric bag about an inflation device incross-section;

FIG. 11 shows the bag system of FIG. 10 with the vertebra in phantom toshow the bag system;

FIG. 12 is a view similar to FIG. 10 showing a different approach to theinterior of the vertebra;

FIG. 13 is a view similar to FIG. 11 showing the approach of FIG. 12;

FIG. 14 shows the bag of FIG. 12 in a closed, filled and expandedposition;

FIG. 15 is a top view of the bag system of FIG. 12 being inflatedthrough a catheter tube;

FIG. 16 shows a femoral head with avascular necrosis;

FIG. 17 shows the femoral head of FIG. 16 being reamed out;

FIG. 18 shows placement of a bag system of the invention within thecavity in the femoral head;

FIG. 19 is a side elevational view of a tibial plateau fracture;

FIG. 20 is a side view of the fracture of FIG. 19 with a cavity beingformed with a reamer; and

FIG. 21 shows the tibial plateau fracture repaired with an expandedinflatable fabric bag in place.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, similar reference numerals areused to depict like elements in the various figures.

FIG. 1 shows a typical vertebra 10 having compression fractures 12 thatis in need of repair. As indicated above the damaged portion of thevertebra 10 may be reamed out, compacted, or otherwise repaired. Forexample, FIG. 2 shows a reamer 14 entering the vertebra 10 anteriorly tomake an opening 15 and cavity 16. Alternatively, multiple cavities 16may be formed such as is shown in FIG. 3.

As previously mentioned, the damaged portion of the vertebra 10 may becompacted in addition to or instead of being reamed out. In FIG. 4, adelivery tube or catheter 20 is seen in the process of delivering anexpandable fabric bag 22 into the vertebra 10 or into a cavity 16present therein. As indicated, the cavity 16 may have been createdthrough reaming, compaction by the bag 22 or other device, or by othermeans. Once the bag 22 is positioned within the vertebra 10, the bag 22may be inflated or expanded to the limits of the cavity 16 thus formedthrough insertion or injection of fill material 19 into the interior 21of the bag 22.

FIG. 5 shows a single filled expandable fabric bag 22 in place with asecond expandable bag which is being inserted and expanded within thecavity 16.

FIGS. 6-9 illustrate a procedure in which the opening 15 and cavity 16are created posteriorly. Regardless of the direction through which thevertebra 10 is operated on, in all forms, the cavity 16 which is formedis then filled with acceptable bone replacement material.

Bone replacement material 19 may be one or more of the following, or anyother biocompatible material judged to have the desired physiologicresponse:

A) Demineralized bone material, morselized bone graft, cortical,cancellous, or cortico-cancellous, including autograft, allograft, orxenograft;

B) Any bone graft substitute or combination of bone graft substitutes,or combinations of bone graft and bone graft substitutes, or boneinducing substances, including but not limited to: Tricalciumphosphates, Tricalcium sulfates, Tricalcium carbonates, hydroxyapatite,bone morphogenic protein, calcified and/or decalcified bone derivative;and

C) Bone cements, such as ceramic and polymethylmethacrylate bonecements.

The bone replacement material is inserted into the bag 22 via a needle,catheter 20 or other type of fill tool. The bone replacement materialexpands the bag to the limits of the cavity 16.

The inventive bag 22 may be a small fabric bag, from about one to aboutfour cm in diameter, being roughly spherical in shape, although otherelliptical shapes and other geometric shapes may be used. The bag ispliable and malleable before its interior space 21 is filled with thecontents to be described. The material of the bag 22 may be configuredto take on the shape of the cavity in which the bag is placed. While inthis initial condition, the bag may be passed, uninflated, through arelatively small tube or portal, perhaps about three mm to about one cmin diameter.

The bag 22, such as may best be seen in FIG. 9, is constructed in aspecial and novel way. The bag 22 may be constructed of a fabric 23.Fabric 23 may be woven, knitted, braided or form-molded to a densitythat will allow ingress and egress of fluids and solutions and willallow the ingrowth and through-growth of blood vessels and fibroustissue and bony trabeculae, but the fabric porosity is tight enough toretain small particles of enclosed material, such as ground up bonegraft, or bone graft substitute such as hydroxyapatite or otherosteoconductive biocompatible materials known to promote bone formation.The fabric 23 defines a plurality of pores 25. Generally, the pores 25of the fabric 23 will have a diameter of about 0.25 mm or less to about5.0 mm. The size is selected to allow tissue ingrowth while containingthe material packed into the bag. If bone cement or other material isused which will not experience bone ingrowth, the pores 25 may be muchtighter to prevent egress of the media from within the bag 22 out intothe cavity 16. This prevents leakage that could impinge upon nerves,blood vessels or the like if allowed to exit the bone.

One or more of the pores 25 may be used as a fill opening 27, whereinthe fabric 23 may be manipulated to enlarge a pore to a diameterpotentially greater than 5 mm but no more than about 1 cm. Preferably,the fill opening 27 is less than about 5 mm in diameter. Such apore/fill opening 27 is sufficiently large to allow a catheter, needle,fill tube or other device for inserting or injecting fill material topass through the fabric 23 and into the interior 21 of the bag 22without damaging the integrity of the bag 22.

When the bag 22 is fully filled with fill material, the bag will form aself-retaining shape which substantially fills the cavity 16. Oncesufficiently full, the fill tool used to place fill material into thebag interior 21 is removed from the opening 27. Where the opening 27 isnot a pore 25 but rather a separate and distinct opening in the bag 22,the opening 27 may have a set diameter which requires sealing such as bytying, fastening, welding, gluing or other means of closing the opening27 after the bag has been filled. Where the opening 27 is a pore 25,upon removal of the catheter or fill tool from the opening 27 the fabric23 will contract to reduce the diameter of the opening 27 to besubstantially similar to that of the other pores 25.

The size and density of the pores determine the ease or difficulty withwhich materials may pass through the mesh. For instance, very smallpores (<0.5 mm) would prohibit passage of all but the smallest particlesand liquids. The pore size and density could be controlled in themanufacturing process, such that the final product would be matched tothe needs of the surgeon. For example, if methylmethacrylate bone cementwere to be used, the pore size would need to be very small, such asabout less than 0.5 mm to about 1.0 mm, whereas, when bone graft orbiocompatible ceramic granules are used, pore sizes ranging from about1.0 mm to about 5.0 mm or more may be allowed. The fact that the fabric23 is properly porous would allow it to restrict potentially dangerousflow of the fill material outside the confines of the bag.

The fabric is light, biocompatible, flexible and easily handled, and hasvery good tensile strength, and thus is unlikely to rip or tear duringinsertion and inflation. When the device is inflated, the device expandsto fill a previously excavated cavity 16.

The use of the term “fabric” herein is meant to include the usualdefinition of that term and to include any material that functions likea fabric, that is, the “fabric” of the invention must have a pluralityof pores 25 through which material and fluid flow is allowed under theterms as described, and the “fabric” must be flexible enough to allow itto be collapsed and inserted into an opening smaller than the inflatedbag size.

The bag 22 need not be woven and may be molded or otherwise formed as iswell known in the art. The preferred material may provide the ability totailor bioabsorbance rates. Any suture-type material used medically maybe used to form the bag 22. The bag may be formed of plastic or evenmetal. In at least one embodiment, bag 22 is formed using a combinationof resorbable and/or nonresorbable thread. Bag 22 may include a fillopening 27 which may be a bushing that could be a bioabsorbable and/ornonbioabsorbable plastic, ceramic or metal. The opening 27 may also behydroxyapatite, or it could be plastic or metal. The opening 27 may alsobe characterized as a pore 25, wherein a pore 25 of the fabric 23 hasbeen expanded to allow a catheter 20 or other fill device to pass intothe interior 21 of the bag 22. The bag 22 could be formed from a solidmaterial to which perforations are added. The bag 22 may be partially ortotally absorbable, metal, plastic, woven, solid, film or an extrudedballoon.

In embodiments of the present invention a damaged tissue of a body, suchas a vertebra 10 may be treated in accordance with the followingprocedures such as are depicted in FIGS. 1-9:

Initially, the vertebra 10 needing repair is surgically exposed byforming at least one cavity 16. The cavity or cavities 16 may be formedby several different means such as by reaming. Reaming may beaccomplished by several means such as including the use of a reamer 14such as, for example, the Kuslich Expandable Reamer, U.S. Pat. No.5,015,255, the entire content of which is incorporated herein byreference. Next, the unexpanded mesh bag or Expandable Fabric Bag Device(EFBD) 22 is inserted into the cavity or cavities via catheter 20 orother means. At some point, the fill material 19 is prepared forinsertion or injection into the EFBD 22. Following preparation of thefill material 19, the material is injected or otherwise inserted intothe bag 22 using sufficient pressure to fill the bag 22 to its expandedstate, thus producing rigidity and tension within the cavity or cavities16 to reach the degree of correction required by virtue of thecompression fractures. Finally, the fill opening 27 is closed to preventegress of inflation material 19.

FIGS. 10-15 show a form of the invention in which a balloon 30 andcatheter tube 32 is employed. The balloon 30 is surrounded by anexpandable fabric bag 22 to protect the balloon 30 from being puncturedduring the inflation steps and to remain in place to prevent undesiredegress of material injected into the cavity formed in the bone. Balloon30 may be any medical-grade elastomeric balloon. The balloon 30 may beconstructed from latex, urethanes, thermoplasic elastomers or othersubstances suitable for use as an expandable member. Examples ofsuitable balloons include, but are not limited to: balloons utilizedwith the FOGARTY.RTM. occlusion catheter manufactured by BaxterHealthcare Corporation of Santa Ana, Calif.; balloons of the typedescribed in U.S. Pat. No. 5,972,015 to Scribner et al., and others. Themethods involve placement of the expandable fabric bag 22 of theinvention about the balloon 30 of the Scribner et al. device. Theexpandable bag 22 is left in place before the cavity 16 is filled withbone substitute or bone cement. The expandable fabric bag 22 preventsbreakage of the balloon 30 and greatly limits the ability of fillmaterial from leaking out of the cavity through bone fissures where itcould cause damage.

As may best be seen in FIGS. 11, 13 and 15, the bag 22 may include aneck 29 which extends outwardly from the bag 22 to completely overlapthe shape of balloon 30. The bag 22 and/or balloon 30 may each have avariety of shapes and sizes.

If desired, the expandable fabric bag 22 may be used as the soleinflation device, eliminating the Scribner et al. balloon 30 if thefabric porosity is tight and the inflation media is reasonably viscous.

While many of the previous embodiments have described the use of the bag22 for repair of tissue such as a spinal body, in FIGS. 16-18 show howthe bag 22 may be used in treating avascular necrosis of the femoralhead. In FIG. 16, a femoral head 40 is shown which is in need of repair.FIG. 17 shows the femoral head being reamed out with a reamer 14, suchas previously described. The reamer 14 forms a cavity 16. In FIG. 18, abag 22 is shown within the cavity 16 formed within the femoral head 40.The opening 27 of the bag 22 is closed off after being filled andexpanded with bone substitute material.

In an alternative embodiment, the Scribner et al. balloon, as previouslydescribed, may also be used with the bag 22 for repair of the femoralhead 40.

Turning to an embodiment of the invention shown in FIGS. 19-21, a tibialplateau 48 is shown having a fracture 50. The fracture 50 is repaired byforming a cavity 16 with a reamer 14, such as is shown in FIG. 20. As isshown in FIG. 21, once cavity 16 is properly reamed, bag 22 may beinserted therein and filled with bone repair media 19.

Other tissue and bone abnormalities may also be treated with theinventive methods and bag 22 described herein. The present invention isnot limited to only treatment of spinal bodies, femoral heads, andtibial plateaus. The bag 22 and the methods of treatment describedherein, may be utilized throughout a mammalian body to treat many typesof bone and tissue abnormalities including those described herein aswell as others.

In addition to being directed to the specific combinations of featuresclaimed below, the invention is also directed to embodiments havingother combinations of the dependent features claimed below and othercombinations of the features described above.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to.” Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein which equivalents are also intended to be encompassedby the claims.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g., each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below (e.g., claim 3 may be taken asalternatively dependent from claim 2; claim 5 may be taken asalternatively dependent on claim 3, claim 6 may be taken asalternatively dependent from claim 3; claim 7 may be taken asalternatively dependent from claims 3, 5 or 6; etc.).

1. A method of treating an vertebral body comprising the steps of:inserting a container into an vertebral body; said container having afill passage coupled to said container; said container having a porousouter membrane sufficiently porous to allow filler material underpressure to leave the container after filling the container; deployingsaid container within said vertebral body injecting a filler materialinto said container through said fill passage with bone filler materialin a sufficient volume to allow the bone filler material to exit thecontainer and interdigitate with cancellous bone within said vertebralbody thereby reinforcing said bone and stabilizing fractures in saidbone; said container membrane porosity sufficient to provide resistanceto the flow of said bone filler material to generate force to move theendplates of said vertebral body.
 2. A method of treating an vertebralbody having a superior endplate and an inferior endplate, comprising thesteps of: inserting a container into an vertebral body; deploying saidcontainer within said vertebral body; injecting a bone filler materialinto said container under pressure; whereby said pressure supplies adistraction force to move said superior and inferior endplates apart;ending injection after said endplates have moved apart.
 3. A method oftreating an vertebral body comprising the steps of: creating a cavity inthe vertebral body through an access aperture; inserting a containerinto said vertebral body; said container having a fill passage coupledto said container; deploying said container within said vertebral body;injecting a bone filler material into said container through said fillpassage.